Pressure switch



Filed Nov. 12, 1954 H. TYZACK 3 Sheets-Sheet 1 66 INVENTOR.

Hqeow 73 2464 5mm 0mm? #am Nov. 19, 1957 H. TYZACK I 2,813,944

PRESSURE SWITCH Filed Nov. 12, 1954 3 Sheets-Sheet 2 36\ V 5 fla IN V EN TOR. Hmow TYZACK Nov. 19, 1957 H. TYZACK 2,813,944

PRESSURE SWITCH Filed Nov. 12, 1954 3 Shets-Sheet 5 IN V EN TOR.

HA Row TYZA cK BY United States Patent M PRESSURE SWITCH Harold Tyzack, Schiller Park, Ill., assignor to Carter Parts Company, Chicago, 111., a corporation of Illinois Application November 12, 1954, Serial No. 468,367

6 Claims. (Cl. 200-83) The present invention relates to a pressure switch, and more particularly to such a switch which is a selfcontained unit for regulating the level of water in a washing machine or the like.

In switches of this character it is desirable that the same be responsive to a plurality of preselected pressures 0 so that it will be operable to fill a washing machine or the like to any desired depth as the situation may rea pressure switch of the foregoing character in which the mechanism for setting the pressure at which the switch is responsive is contained within the housing of said switch, said mechanism being sturdy in construction and sensitive in operation so that uniformly consistent operating results will be obtained.

It is still another object of the present invention to provide a pressure switch of the foregoing character in which the pressure setting mechanism can have an infinite number of settings, if desired.

'Other objects of this invention will appear in the following description and appended claims, reference being had to the accompanying drawings forming a part of this specification wherein like reference characters designate corresponding parts in the several views.

In the drawings: Fig. l is a bottom view of one embodiment of the present invention;

Fig. 2 is an enlarged section taken on the lines 22 of Fig. 1;

Fig. 3 is a section taken on the line 33 of Fig. 2;

Fig. 4 is a plan view of the embodiment shown in Fig. 1;

Fig. 5 is a section taken on the line 55 in Fig. 2; and

Fig. 6 is a sectional view similar to that of Fig. 2 of a modified form of the invention.

Before explaining the present invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also, it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

Referring now to the drawings a more detailed description of the invention will be given. The pressure switch includes a housing or casing 10 which is divided to form a switch chamber 12 and a pressure chamber 14. The casing 10 may be made from any suitable material, but preferably the portion 16 forming the switch chamber 12 is of molded plastic and the portion 18 forming the pressure chamber 14 is a sheet metal stamping. A pressure 2,813,944 Patented Nov. 19, 1957 fitting 22 is soldered or welded in place centrally of the sheet metal stamping which forms the portion 18. The outer end of pressure fitting 22 has an aperture 23 over which a flexible tube or hose (not shown) may be connected to transmit fluid pressure to the chamber 14.

Clamped in place between the portions 16 and 18 by the flange 24 is a resilient diaphragm 26 which separates the pressure chamber 14 and the switch chamber 12. A relatively stiff metal disk 28 maintains the central portion of the diaphragm 26 relatively fiat and serves to transmit pressure from within the pressure chamber 14 to a switch actuating mechanism as will be described.

A snap-acting switch element 30 is mounted within the switch chamber 12. It includes the adjustable arms 32 and 34 which are connected to the plastic portion 16 by the rivets 36 and 38. The opposite ends of these arms are in engagement with adjusting screws 39 and 40 which can be screwed in or out to change the position of the stationary contacts 42 and 44 which are mounted, respectively, on the lateral projections 46 and 48 of the aforesaid arms 32 and 34. It will be noted that the adjusting screw 39 is somewhat longer than adjusting screw 40 and that the arms 32 and 34 are mounted so that the lateral projections 46 and 48 are in different planes. Thus, the contacts 42 and 44 are in axial alignment but are spaced apart so that a movable contact can move therebetween.

Mounted laterally between the arms 32 and 34 by a rivet 50 is a resilient contact carrying arm 52 which has a U-shaped aperture 54 cut therein so as to form a spring arm 56. The edges of thesearms are partially turned so that movement of the free ends thereof occurs primarily through pivotal action occurring at the bases thereof near the rivet 50. The free ends of arms 52 and 56 are operatively connected by a U-shapedspring 58 which exerts a thrust between the free ends of arms 52 and 56 so that arm 56 will tend to snap upwardly or downwardly as it passes through the plane of arm 52.

Carried on the end of arm 52 is a contact 60 which will snap into engagement with either of stationary contacts 42 and 44, depending upon the direction of movement of arm 52. Electric terminals 62, 64 and 65 are mounted on the external surfaces of the casing 10 and are connected electrically to the contacts 42, 44 and 60. Thus, an electric circuit can be closed between terminals 62 and 66 or 64 and 65 by movement of contact 60 into engagement with contacts 42 or 44.

The spring arm 56 is actuated to one or the other of its operating positions by axial movement of the actuating pin or actuator 66 which can be attached to the spring arm 56 in any suitable manner. In the embodiment disclosed the arm 56 has an aperture through which the actuator initially is passed and the arm 56 can be clamped between the lugs 68 and the shoulder 70.

The one end of the actuator 66 is rounded and in engagement with a socket or recess 72 at the center of the metal disk 28. The other end of the actuator 66 is enlarged to provide a sliding fit in the opening 74 of casing 10, and is formed from any dielectric material such as rubber or a suitable plastic. From the foregoing it can be understood that the snap-acting switch element 30 will be actuated so that the contact 60 is snapped into engagement with contact 42 when pressure is exerted from the pressure chamber 14 against the diaphragm 26 thereby moving the actuator 66 to the right as seen in Fig. 2, and conversely, the contact 60 will be snapped back to the position shown in Fig. 2 when the actuator is urged to the left against the action of diaphragm 26.

The control mechanism for determining the pressure that must be exerted against diaphragm 26 is contained within the boss 76 formed integrally in the wall of ms ing 10. The boss 76 is hollow and one end of the actuator 66 extends thereinto through the opening or passage 74. Telescoping over the one end 'of actuator 66 is a cylinder 78 closed atits other end. A coil spring 80 is operatively positioned between the actuator 66 andthecylinder 7.3 for. urgingthe same apart. "Another coil spring.,8'2.is disposed-betweenthe shoulder 84 of casing 10 and the outwardly projecting shoulder 860i cylinder 78for urging the latter, to the right for a purpose to be explained;

Fitted? intothe hollow. boss 76 .is a circular cam member 88 whichha's. two sets of cam surfaces 90 on diametrically opposite sides, which are adapted to receive acamfollower 912, Fig. ,.which is rigidly connected to the closed end of cylinder 78. Thus, if cylinder 78 is rotated about its.axis, the ends of cam follower 92 will travel on the diametrically. opposed cam surface 96 causing thecylinder '78.to move axially toward or away from the actuator 66, the. spring 82 urging the cam follower 92 into. continuous contact with said cam surfaces 90.

The cylinder78 canrbe, rotatedin any suitable manner, the disclosed modificationutilizing a slotted end portion 94 which. is integral with the. closed end of the cylinder. A tongue 96 .projects,fr'omltlie end of the handle 98 into the slot so that turning of'handle 98 causes the cylinder 78 .to'be' turned on its axis. The control mechanism is retained within the hollow boss 76 by the cover 100 which isa part of the, bracket 102, the latter having a sleeve 104 through which the handle 98 is passed in assembling the unit. A retainer spring 106 carried in a groove in handle 98 holds the latter in its operative position.

Inthe operation of the embodiment of the invention of Figs. 1 to 5., air or another suitable fluid enters the inlet port 23 of the pressure chamber 14 from a device being controlled and exerts pressure against the diaphragm 26. This causes movement of the diaphragm 26 and the actuator 66 to the right as viewed in Fig. 2. Due to the construction shown, the spring arm 56 is also moved. When this movement is great enough the arm 56 comes to a position of equilibrium with the arm 52, and thereafter any increase of pressure in chamber 14 will cause the U-shaped spring 58 to snap the contact arm 52 from its position in Fig. 2 to a position wherein the contact 60 engages contact 42.

The conrtol mechanism in the hollow boss 76 permits different settings so that prescribed or predetermined pressures within the pressure chamber 14 will actuate the switch element 30. This is accomplished by turning handle 98 to any selected position whereby different cam positions of the cam member 88 are utilized. Such action has the eifect of changing the compressive forces of coil spring 80 so that greater or lesser pressures are exerted by suchspring against the action of the diaphragm 26. In order to obtain sensitive operation of spring 80, an adjusting screw 108 is provided.

While it is generally desirable to provide a pressure switch having means for varying the pressures at which itwill be actuated, the present unit can be made so that it is responsive to only one preselected pressure. Such an embodiment is shown in Fig. 6. In this embodiment, like reference, numbers are used to indicate like parts of the embodiment shown. inFigs. l'to 5.

'As can be seen, the embodiment of Fig. 6 difiers only in the constructionof the mechanism contained within the hollow boss 76. .In the present unit a cover 110 closes the open end of the boss 76 and a single sleeve 112. is disposed. between the cover 110 and the shoulder in the boss76 adjacent opening or passage 74. The actuator 114.slidab1y fitsinto. the sleeve 112 and is urged at a constant pressure against diaphragm 26 by the coil spring 116.

.Havingthus described. my. invention, I claim:

1., Apressure. switc'hc'omprisinga casing with a control-chamber formed. in one; wall, a pressure operated diaphragm. mounted-withinv said. casing. to form a pressure chamberon.one:;side.and;aswitch chamber on the other side thereof, a snap-acting switch in said switch chamber including a switch arm movable between two operative positions, an acfilator connected intermediate its ends to said switch arm for moving the latter to one or the other of its operative positions, one end of said actuator operatively contacting said diaphragm and the other end extending through a passage in said one wall into said control chamber, a spring retainer member adjustably mounted in said control chamber, a spring mounted in compression between said retainer member and said actuator for urging the latter against the diaphragm with a fixed pressure, an adjusting mechanism within said control chamber for selectively varying the position of said retainer member so as to vary the pressure exerted by said spring against said diaphragm, and a second spring mounted between said spring retainer and said one Wall for urging the spring retainer into operative association with said adjusting mechanism.

2. In a pressure switch having a fluid pressure responsive mechanism for actuating a snap-acting switch, acontrol mechanism comprising a springfor setting, the effective pressure at which, said-fluid pressure responsive mechanism actuates said snap-acting switch,v a spring retainer for retaining said spring in one of several selective. compression settings, a. circular cam. coaxially disposed withrespect to said spring, and a rotatable camfollower mounted on said spring retainer and in engagement with said circular cam so that on rotation of the cam follower the effective pressure at which the pressure responsive mechanism actuates the snap-acting switch can be varied.

3. In a pressure switch having a casing with a control chamber formed within one wall, a pressure operated diaphragm, a snap-acting switch responsive to movements of said diaphragmand anactuator connected to saidsnapacting switch and responsive to movements of said diaphragm to snap said switch, a control mechanism carried in the control chamber comprising a rotatable spring retainer coaxially aligned with said actuator, a-coil spring compressed between said retainer and said actuator to urge the latter against said diaphragm at apredetermined pressure, a cam follower carried by said retainer, anda cam engaging said follower so that on rotation of said retainer the latter will be moved axially to'vary the predetermined pressure exerted by the actuator on said diaphragm.

4. In a pressure switch having a casing with a control chamber formed within one wall, a pressure operated diaphragm, a snap acting switch responsive to movements of said diaphragm and an actuator connected to said snap-acting switch andresponsive to movements of said diaphragm to snap said switch, a control mechanism carried in said control chamber comprising a rotatable spring retainer coaxially aligned withsaid actuator, a coil spring compressed between said retainer and said actuator to urge the latter against said diaphragm at a predetermined pressure, a cam follower carried by said retainer, and a circular cam. having a plurality of axially staggered cam surfaces for selective engagement by said cam follower, and a handle'connected to said rotatable spring retainer for placing the latter in any selected rotatable position.

5. A pressure switch comprising a casing with a'control chamber formed in one of its walls, a pressure operated diaphragm mounted within said casing to form a pressure chamber on one side and a switch chamber on the other side thereof, said control chamber having an external opening and communicating with said switch chamber by a passage in the casing wall, a snap-acting switch in said switch chamber including a switch arm movable between two. operative positions, an actuator connected intermediate its ends to. said switch arm for moving the latter to one, or the other of-its operative positions, one, end of, saidactuator operativelycontacting said diaphragm and, the other end extendinginto ..the

passage in the casing wall, said control chamber including a cylindrical portion in axial alignment with said diaphragm and in which is adjustably mounted a spring retainer member, a spring mounted in compression between said retainer member and said actuator for urging the latter against the diaphragm with a fixed pressure, a circular cam mounted in said cylindrical portion and having a plurality of axially staggered cam surfaces, a cam follower on said retainer member for following said cam surfaces so that on rotation of the retainer member the pressure exerted by said spring against said diaphragm can be varied, and a closure member fitting over the external opening of said control chamber.

6. A pressure switch comprising a casing with a control chamber formed in one wall, a pressure operated diaphragm mounted within said casing to form a pressure chamber on one side and a switch chamber on the other side thereof, a snap-acting switch in said switch chamber including a pair of spaced contacts adjustably supported from the wall of said casing with adjusting means extending through said wall and a switch arm extending generally parallel to said diaphragm and mounted at one end on the wall of said casing, the other end being movable between said spaced contacts, an actuator rod extending normal to said diaphragm and connected intermediate -its ends to an intermediate portion of said switch arm for moving the latter to one or the other of said contacts, one end of said actuator rod operatively contacting said diaphragm and the other end extending through a passage in said wall into said control chamber, a spring retainer member adjustably mounted within said control chamber, a spring in said control chamber carried in compression between said retainer member and said actuator rod for urging the latter axially against the diaphragm with a fixed pressure, and adjusting means within said control chamber for selectively varying the position of said retainer member to predetermined fixed position so as to vary the efiective pressure exerted by said spring against said diaphragm.

References Cited in the file of this patent UNITED STATES PATENTS 2,087,122 Scherer July 13, 1937 2,179,285 Eaton Nov. 7, 1939 2,231,218 Palmer Feb. 11, 1941 2,440,690 Jacobi May 4, 1948 2,595,967 McCloy May 6, 1952 2,598,563 Konle et al. May 27, 1952 2,636,093 Clark et al. Apr. 21, 1953 2,720,564 Soreng et al. Oct. 11, 1955 2,755,362 Jacobs July 17, 1956 

